"Per se" laws in DUI or DWI cases generally establish that once an individual is shown to have a blood-alcohol concentration (BAC) at or above .08 percent, that person will be considered intoxicated by law. In such circumstances, no further evidence of intoxication or impairment need be demonstrated for purposes of a DUI case. These days, all states have per se DUI laws that find any driver with a blood-alcohol concentration (BAC) at or above .08 percent to be intoxicated.

The existence of these laws throughout the United States means that it is important for individuals who are drinking to realize that, regardless of how sober they themselves feel and behave, it is their BAC that matters in the eyes of the law once they get behind the wheel. Should it exceed the per se legal limit, they will legally be presumed to be impaired. These laws make it easier for the prosecution to establish that an individual was impaired, without requiring much on-scene evaluation such as sobriety testing and the like.

Challenging the Results of a Blood or Breath Test

Still, these laws do not mean that all defendants who register a .08 BAC or higher face an "open and shut" scenario as far as their DUI case is concerned. For example, defendants can and do challenge everything from the validity of test results to the machines used to collect these results and the procedures used. A variety of other defenses in criminal DUI cases also exist, which can be raised before or during trial.

Drugs and Per Se Laws

The BAC limits established by per se DUI laws do not address driving under the influence of drugs. However, a growing number of states have per se laws addressing drugged driving. The states which have these types of laws on their books are Arizona, Delaware, Georgia, Illinois, Indiana, Iowa, Michigan, Minnesota, Nevada, Ohio, Pennsylvania, Rhode Island, Utah, Virginia and Wisconsin. Of these, three states (Nevada, Ohio, and Virginia) establish specific limits for the presence of intoxicating drugs, while the rest establish a zero tolerance rule with regards to the presence of intoxicating drugs in a person's system.

In addition to the challenges that can be raised in DUI cases, prosecutions under per se laws in drug cases face the added challenge of having to establish the presence of a particular listed type of prohibited substance in a defendant's system. While alcohol comes basically in one form, drug testing and analysis can sometimes be a bit more complicated. The fact that certain drugs remain in a user's system for days or even weeks after their intoxicating effects have worn off complicates matters even more.

Underage Drivers and Zero Tolerance

Underage drivers often are faced with even more strict measures than standard per se BAC levels. Motorists under the legal drinking age often face "zero tolerance" rules that make it illegal to test for absolutely any amount of alcohol concentration in their blood. The rationale behind these laws is that drinking alcohol is prohibited for those under the age of 21 and thus any amount of alcohol in an underage driver's system should be punished. These types of offenses typically result in the loss of driving privileges, to varying degrees.

Have Questions About Per Se DUI Laws? Ask an Attorney

If you've been arrested for a per se DUI, you may need legal representation, especially if you want to contest the blood or breath test results. Contact a local DUI attorney today to find out the strengths and weaknesses of your case and be better prepared to make crucial decisions going forward.

Next Steps

Contact a qualified DUI attorney to make sure your rights are protected.